Imaging of a large field of view at the same instant is required for a wide variety of applications. Security cameras, for instance, are usually very limited in their field of view; therefore rotation/pan-tilt mechanisms are often implemented to enable accumulative coverage of the desired wide field of view. Inner body imaging during medical endoscopy procedures also represents a need to view as large field of view as possible, in order to achieve proper orientation while maneuvering the medical endoscope inside the body. Additional applications exist, and they all suffer from the currently limited field of view, which is provided by the lenses that are implemented in the image capture device.
As a result of the specified problems, prior art has provided methods of enlarging the field of view which is covered by an image capture device, by utilizing axi-symmetric reflective surfaces, which reflect a cylindrical field of view towards the image capture device. An example for such a method is described in Publication No. US 2002/0126395.
A more complex method is described in Publication No. US2001/0010555 and includes a design of a mirror assembly, comprised of two reflective surfaces and provides coverage of a cylindrical field of view.
Additional methods were presented, in order to enlarge the field of view beyond cylindrical. U.S. Pat. No. 6,028,719 describes the use of an axi-symmetric reflective surface with a hole in its center to achieve coverage of two scenes—a cylindrical scene which is reflected from the surface, and an additional scene, which is above the cylindrical scene, which penetrates through the hole and captured simultaneously by the same image capture device, thus a hemispherical field of view may be captured.
An improved method for capturing a hemispherical field of view is described in publication no. WO 02/059676, which is incorporated herein by reference.
Furthermore, the art has presented a method for acquiring a cylindrical field of view, together with an optically zoomed sector simultaneously. The method described in Publication No. WO 03/026272, which is incorporated herein by reference, makes use of an axi-symmetric reflective surface that reflects a cylindrical field of view towards an image capture device and an additional reflective surface which reflects an optically zoomed sector towards the same image capture device simultaneously.
Additional methods which rely on the use of an axi-symmetric reflective surface were presented, all rely on the concept of reflecting a large field of view towards an image capture device, and some include performing image processing to convert the image to a shape suitable for a human viewer.
It is therefore an object of the present invention to provide significant improvement to wide-angle image capture devices, by enlarging the field of view which is covered simultaneously.
It is further an object of the present invention to provide electro-optical structures that provide hemispherical, nearly spherical or spherical field of view coverage.
It is yet another object of the present invention to provide a method for achieving optical zoom of a sector, while continuously imaging a nearly spherical field of view.
Other objects of the invention will become apparent as the description proceeds.